Re: LuaJIT 64 bit integers (was: the purpose of lightuserdata)

[Leo Razoumov <slonik.az@...>]

On Thu, Jan 13, 2011 at 13:51, Josh Haberman <jhaberman@gmail.com> wrote:
> Roberto Ierusalimschy <roberto <at> inf.puc-rio.br> writes:
>> > Yes, I shudder to think of explaining that to users.  I was initially
>> > very excited to hear your announcement of 64-bit integer support since
>> > it's been a stumbling block for adoption of Lua inside Google where we
>> > have lots of 64-bit integers floating around, [...]
>>
>> We have discussed in the list how to compile Lua to use long doubles so
>> that regular numbers can represent 64-bit integers. Isn't that enough
>> for you?
>
> That's definitely one option; the most obvious downside of that is
> that long double takes up twice the memory of double or int64.
>

If memory consumption per long double is a concern, GCC offers
-m96bit-long-double option. On x86_64 it will incur a slight
performance penalty though, and one needs to be very careful, for this
flag changes ABI.

--Leo--